STRUCTURE AND SYNTHESIS OF THE 1ST FLAVONOID-RELATED AND STILBENE-RELATED BUT-2-ENOLIDES

The structures of the first flavonoid- and stilbene-related but-2-enolides [furan-2(5H)-ones] have been established as 3-(2,4-dihydroxyphenyl)-4-(4- hydroxybenzyl)but-2-en-4-olide and 3-(3,5-dihydroxystyryl)-4- methoxycarbonylmethylbut-2-en-4-olide, respectively. Confirmation of the structure of the hydroxybenzyl product and hence demonstration of its relationship to the flavonoids was achieved by intramolecular aldol-type reaction of an α-acetoxydihydrochalcone. 3-(3,5-Dihydroxystyryl)-4- methoxycarbonylmethylbut-2-enolide presumably represents a degradation product of 3,3′,4,5′-tetrahydroxystilbene.